Cell-based interconnect migration by hierarchical optimization

Fueled by Moore's Law, VLSI market competition and economic considerations dictates the introduction of new processor's microarchitecture in a two-year cycle called “Tick-Tock” marketing strategy. A new processor is first manufactured in the most advanced stable process technology, followed in a one-year delay by introducing chips comprising same microarchitecture but manufactured in a newer scaled process technology, thus allowing higher production volumes, better performance and lower cost. Tick-Tock is enabled by the automation of chip's layout conversion from an older into a newer manufacturing process technology. This is a very challenging computational task, involving billions of polygons. We describe an algorithm of a hierarchy-driven optimization method for cell-based layout conversion used at Intel for already several product generations. It transforms the full conversion problem into successive problems of significantly smaller size, having feasible solutions if and only if the full-chip problem does. The proposed algorithm preserves the design intent, its uniformity and maintainability, a key for the success of large-scale projects.     

Do generation firms in restructured electricity markets have incentives to support social-welfare-improving transmission investments?

This paper examines the incentives that generation firms have in restructured electricity markets for supporting long-term transmission investments. In particular, we study whether generation firms, which arguably play a dominant role in the restructured electricity markets, have the incentives to fund or support incremental social-welfare-improving transmission investments. We examine this question in a two-node network and explore how such incentives are affected by the ownership of financial transmission rights (FTRs) by generation firms. In the analyzed two-node network, we show both (i) that the net exporter generation firm has the correct incentives to increase the transmission capacity incrementally up to a certain level and (ii) that, although a policy that allocates FTRs to the net exporter generation firm can be desirable from a social point of view, such a policy would dilute the net-importer-generation-firm's incentives to support transmission expansion. Moreover, if all FTRs were allocated or auctioned off to the net exporter generation firm, then it is possible to increase both consumer surplus and social welfare while keeping the net exporter generation firm revenue neutral.     

Treatment of internal constraints by mixed finite element methods: Unification of concepts

A general method to generate assumed stress and strain fields within the context of mixed finite element methods is presented. The assumed fields are constructed in such a way that internal constraints are satisfied a priori. Consequently, the locking behaviour commonly observed in finite element solutions of problems with internal constraints is avoided. To this end, the assumed stress and strain fields are constructed to satisfy a priori the homogeneous part of the equilibrium equations, thus avoiding Fraeijs de Veubeke's limitation principle. Results obtained using the proposed methodology on a nearly incompressible plane strain problem and thin plate application using a shear deformable theory are indicated.     

A lower bound on the period length of a distributed scheduler

Ad-scheduling of a graphG is a sequence of rounds, each consisting of some of the nodes of the graph, such that the distance between any two nodes participating in the same round is greater thand. Ad-scheduler is a protocol that determines ad-scheduling ofG. A 1-scheduler is applicable to process scheduling in a resource-sharing system, and to proper communication scheduling of the half-duplex model in communication networks. A 2-scheduler can be used as a collision-free protocol for radio networks.In this paper a simpled-scheduler is analyzed. We first discuss basic properties of this scheduling, and give a complete characterization of this scheduling for trees and cycles. We study the period length of this scheduling, and the main result is a worst-case exponential lower bound for this length.The research of Shmuel Zaks was supported by the Fund for Research in Electronics, Computers, and Communications adminstered by the Israeli Academy of Sciences and Humanities.     

Appraising fairness in languages for distributed programming

The relations among various languages and models for distributed computation and various possible definitions of fairness are considered. Natural semantic criteria are presented which an acceptable notion of fairness should satisfy. These are then used to demonstrate differences among the basic models, the added power of the fairness notion, and the sensitivity of the fairness notion to irrelevant semantic interleavings of independent operations. These results are used to show that from the considerable variety of commonly used possibilities, only strong process fairness is appropriate forCSP if these criteria are adopted. We also show that under these criteria, none of the commonly used notions of fairness are fully aceptable for a model with an n-way synchronization mechanism. The notion of fairness most often mentioned for Ada is shown to be fully acceptable. For a model with nonblockingsend operations, some variants of common fairness definitions are appraised, and two are shown to satisfy the suggested criteria. Krzysztof R. Apt was born in 1949 in Poland. Received his Ph.D. in 1974 from Polish Academy of Sciences in Warsaw in mathematical logic. From 1974 until 1981 worked at various scientific institutions in the Netherlands and from 1981 until 1987 at C.N.R.S. in Paris, France. Spent 1985 as a visiting scientist at IBM Research Centre in Yorktown Heights, U.S.A. Currently holding an Endowed Professorship at the Department of Computer Sciences at the University of Texas at Austin; also a senior research scientist at the Centre for Mathematics and Computer Science in Amsterdam, the Netherlands. His research interests include program correctness and semantics, methodology of distributed computing, use of logic as a programming language and non-standard forms of reasoning. He has served on editorial boards of a number of journals and program committees of numerous conferences in computer science. Lectured in a dozen countries on four continents. Also, he has run two marathons and crossed Sumatra on a bicycle. Shmuel Katz received his B.A. in Mathematics and English Literature from U.C.L.A., and his M.Sc. and Ph.D. in Computer Science (1976) from the Weizmann Institute in Rehovot, Israel. From 1976 to 1981 he was a researcher at the IBM Israel Scientific Center. Presently, he is a Senior Lecturer in the Computer Science Department at the Technion in Haifa, Israel. In 1977–78, he visited for a year at the University of California, Berkeley, and in 1984–85 was at the University of Texas at Austin. He has also been a consultant for the MCC Software Technology Program. His research interests include the methodology of programming, specification methods, program verification and semantics, distributed programming, data structures, and programming languages. Nissim Francez received his B.A. in Mathematics and Philosophy from the Hebrew University in Jerusalem, and his M.Sc. and Ph.D. in computer science (1976) from the Weizmann Institute of Science, Rehovot, Israel. In 1976–77 he spent a postdoctoral year at Queen's university, Belfast, where he was introduced by C.A.R. Hoare to CSP. In 1977–78 he was an assistant professor at USC, Los Angeles. From 1978 he is with the Computer Science Department at the Technion. In 1982–83 he was on a sabbatical leave at IBM T.J. Watson Research Center. He has been a consultant for MCC's software technology program, working on multiparty activities in distributed systems. He had summer appointments in Harvard University, IBM T.J. Watson Research Center, Utrecht University, CWI (Amsterdam) and at MCC. He also served in several program committees. His research interests include program verification and the semantics of programming languages, mainly for concurrent and distributed programming. Is also interested in logic programming and recursive query evaluation and in compiler constration. He is the author of the first book onFairness. Unfortunately, he is incapable of Marathon running...     

Pyridine‐Modified Polymer as a Non‐Covalent Compatibilizer for Multi‐Walled CNT/Poly[ethylene‐co‐(methacrylic acid)] Composites Fabricated by Direct Melt Mixing

Multi‐wall CNT/poly[ethylene‐co‐(methacrylic acid)] composites were prepared by melt mixing. To improve dispersion and promote polymer/nanotube interactions, a novel non‐covalent compatibilizer is synthesized by reacting the polymer with 4‐(aminomethyl)pyridine. The composite based on the pristine polymer shows electrical and rheological percolation thresholds at nanotube loadings of 1.85 and 1.4 wt%, respectively. When 5 wt% of the pyridine‐modified compatibilizer is added, the corresponding values are reduced to 1.44 and 0.8 wt%, respectively. The electrical resistivity decreases even further as 10 wt% of the novel dispersing agent is used. Microscopy and Raman spectroscopy confirm the improved dispersion and π‐interactions established during melt mixing.

     

Thermal stability of nano Ce1−xTixO2 material system for X < 0.2

Ceria (CeO₂) is a technologically promising compound due to a remarkable set of properties. However, the use of ceria also has drawbacks, the most pronounced of which is the material's poor thermal stability. This property limits the use of ceria-based materials at elevated temperatures, in many technological applications. To overcome this, the addition of TiO₂ is proposed. Such addition essentially creates a new material system, namely Ce_1−xTi_xO₂. In this work, an array of techniques were employed to determine the thermal stability of this new compound range (X < 0.2). Results show that when nano-sized, TiO₂ is fully soluble in CeO₂ in this range. After heat treatment, however, the material coarsens and the solubility limit decreases to less than 2 at.%. as the compound undergoes significant changes. These include solute segregation and phase separation. Finally, the factors that affect compound stability are discussed.     

The Effect of Particle Size Distribution on the Microstructure and the Mechanical Properties of Boron Carbide-Based Reaction-Bonded Composites

The presence of unreacted, free silicon lowers the mechanical properties of reaction-bonded boron carbide. The fraction of free silicon can be reduced by increasing the green density of the initial boron carbide performs. The use of multimodal boron carbide mixtures allows attaining 75% green density. After reaction bonding with molten silicon, the composites consist of four phases, namely the original B₄C particles, the B₁₂(B,C,Si)₃ phase, product of the dissolution–precipitation process, β-SiC, and residual Si. The volume fraction of residual Si in the composites is in the 8–10% range. The infiltrated composites display elevated values of the mechanical properties with a high Weibull modulus.     

Orientation-Dependent Tensile Behavior of Nanolaminated Graphene-Al Composites: An <Emphasis Type="Italic">In Situ</Emphasis> Study

We conducted in situ microtension experiments in a scanning electron microscope (SEM) to study the orientation-dependent mechanical behavior of nanolaminated graphene-Al composite. We found a transition from a weak-and-brittle behavior in the isostress composite configuration to a strong-yet-ductile tensile response in the composite under isostrain condition. This is explained by the excellent load-bearing capacity of the graphene nanosheets and a crack deflection mechanism rendered by the laminate structure. These in situ measurements enabled direct observation of the deformation procedure and the exact failure mode, which highlight the importance of microstructural control in tailoring the mechanical properties of advanced metal matrix composites (MMCs).     

Synthesis of multivariable,basically non-interacting systems with significant plant uncertainty

This paper presents a synthesis technique for basically non-interacting, time-invariant, linear, minimum-phase, multi-variable feedback control systems with significant plant uncertainty. The technique permits precise design to specifications in the frequency domain, of the form k_i¹(ω)?|τ_ii(jω)|?k_i²(ω), |τ_ij(jω)|?k_ij(ω), i/n=j, to be satisfied over the range of plant parameter uncertainty, where T = [τ_αβ] is the matrix of transfer functions of the closed-loop system, and the k's are a priori specified. The specifications are achieved with loop transmission elements of minimum ‘bandwidth’.A computerized iteration scheme is developed. At each iteration the problem is one of designing separate, single input-output systems with parameter uncertainty. An exact synthesis technique exists for this problem. Two detailed examples are given: one, a rotating d.c. to a.c. converter, in which parameter uncertainty is by a factor of 10 (1000%) and the second with parameter uncertainty factors up to 100.